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Author
Title Acoustic metafluid with anisotropic mass density and tunable sound speed
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Publication Date
Degree MS
Discipline/Department Mechanical and Aerospace Engineering
Degree Level masters
University/Publisher Rutgers University
Abstract Metamaterials are artificially synthesized materials with uniquely engineered properties that do not occur in nature. Fabrication of such materials for application to acoustics has led to the creation of novel media with distinct bulk modulus and mass density characteristics. Studies in this field have typically examined how the properties of these unique materials can be used to manipulate either the attenuation or speed of a propagating sound wave. Previous works have used rigid structures with fluid cavities as a means to achieve changes in the acoustic behavior of the system. These approaches have resulted in the successful fabrication of materials with anisotropic mass density as well as advanced theoretical considerations for the creation of materials with anisotropic bulk modulus. This work uses a different approach to achieve anisotropic mass density, by creating a metafluid consisting of orientable anisotropic ferromagnetic particles. The anisotropy of the mass density is achieved through the induced mass of the particles, which varies with the particles’ alignment relative to the direction of wave propagation. The successful manipulation of the speed of sound is experimentally demonstrated for the two particle orientations examined, namely that of parallel and perpendicular alignment. The changes in the speed of sound are found to vary with frequency, confirming that the induced mass is the governing mechanism of the mass density anisotropy. Comparison of the experimental data to theoretical predictions reveals higher-than-expected variations in the acoustic wave speed. This behavior is qualitatively accounted for through experimental evidence that indicates particle-particle interactions, resulting in chained particle structures that effectively behave as a single particulate with larger dimensions. Furthermore, experimental investigations reveal that the magnitude of anisotropic wave speed can be controlled through the intensity of the external magnetic field used to align the particles.
Subjects/Keywords Metamaterials; Acoustical engineering
Contributors Seitel, Mark Joseph, 1987- (author); Shan, Jerry W. (chair); NORRIS, ANDREW (internal member); Tse, Stephen D. (internal member)
Language en
Country of Publication us
Format xv, 96 p. : ill.
Record ID oai:example.org:rutgers-lib:36657
Other Identifiers rutgers-lib:36657; ETD_3765; doi:10.7282/T3W0950N
Repository rutgers
Date Indexed 2019-08-21

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